As mentioned in your other thread on the same topic:
No and Yes.
The /boot/efi is not a partition; in fact, it’s only the mount point that points to the $ESP location. However, the fat32 EFI System Partition (ESP) that it points to should indeed be the $ESP.
In most cases, you don’t (it’s generally not recommended); however, some like to create an extra partition to overcome some perceived difficulties.
That I can’t help you with, but I can point out a few things I’ve noticed, which may be of interest to others wishing to help:
/dev/nvme0n1p3 appears to be an extended partition type. This might indicate that the disk partitions were created atop an MSDOS/MBR partition table. For the purposes of UEFI booting, the $ESP and all patitions need to be created on a GUID Partition Table (GPT).
Because of this, the (ESP) partition would be invalid; just a plain fat32 formatted partition, instead of a fully qualified #ESP.
To further support this, I note that /dev/nvme0n1 clearly shows a DOS/MBR partitioning scheme.
With an LVM2 configuration also thrown into the mix, I don’t know of an easy way to recover from this situation, without a full reinstallation using recommended settings.
Perhaps someone might be kind enough to point you in the right direction; to install Manjaro purely as UEFI; and how to make the correct choices before and during installation.
Manjaro Install media must alo boot in UEFI mode. 
I’m afraid I might not have the time, or patience.
Good luck.
Please see: